This invention relates generally to solid-state electronic timepieces having an electro-optic display formed by light-emitting read-out elements and capable of selectively presenting different functions of time in a Time-mode, each of which is settable in a Set-mode, and more particularly to a solid-state timepiece in which the display in either mode automatically shuts off.
The term solid-state electronic timepiece, as used herein, is limited to timepieces provided with an electro-optic time display and having no moving parts.
In one well-known form of a solid-state electronic watch, electrical pulses derived from a crystal-controlled time base serve to actuate a multi-digit, electro-optic display formed by light-emitting diodes (LED). In such solid-state watches, the high-frequency output of the time base is fed to a frequency converter constituted by a chain of integrated-circuit divider stages. The low-frequency timing pulses yielded in the output of the frequency converter are applied to a display actuator in the form of a miniature time-computer module that counts the input pulse train, encodes it in binary form and then decodes and processes the results so as to provide the appropriate indications at the several display stations.
In a solid-state watch having an LED display, the power requirements for the display are quite high; hence should the display be kept on continuously, the life of the battery would be brief. It is for this reason that commercially-available solid-state watches having an LED display are provided with a normally-quiescent display that is turned on only when the user depresses a push-button demand switch, thereby conserving power and prolonging the life of the battery.
In one such LED watch, as disclosed, for example, in U.S. Pat. No. 3,756,013, the LED display is programmed so that upon merely touching the push-button switch, the minutes and hours are indicated for an interval of one and one-quarter seconds, whereas continued depression of the switch causes the minutes and hour data to fade and the seconds to appear, the seconds continuing to count as long as the demand button is held in. In this solid-state timepiece, precise computation or time is continuous and independent of whether or not it is displayed, so that the moment the switch is depressed, timing signals are applied to the display.
In solid-state watches of the type disclosed, for example, in U.S. Pat. Nos. 3,756,013 and 3,759,031, setting of the various readings is accomplished by separate switches, one for "hours" and the other for "minutes." The term "reading" as used herein, as distinguished from function, refers to a single component of a function. Thus an Hours-Minutes function is composed of an Hours reading and a Minutes reading. These setting switches are actuated by inserting a probe in a recess giving access thereto. When the "hours" set switch is operated, the "hours" read-out advances rapidly without disturbing the setting of the minutes and seconds. When the "minutes" setting switch is actuated, the "seconds" are automatically zeroed, while the minutes are advanced to the desired setting. When the probe is withdrawn, the setting switch is de-activated. When the display includes other time functions such as the calendar month and date, still other switches are required.
The need for a separate, mechanically-actuated setting switch for each of several time functions unduly complicates the watch structure and makes it difficult for the user to carry out setting operations. To avoid this difficulty, it is known to use a single, button-operated switch for setting all of the time functions. An example of this type of solid-state watch is the LSI-010 LED watch movement manufactured by LSI Systems, Inc., of Sunnyvale, Calif. (hereinafter referred to as the LSI movement), this movement being incorporated in watches sold under various commercial brand names.
The LSI movement is a multiplexed, four-digit, solid-state device that displays, on demand, the following three time functions in digital terms: Hours-Minutes, Minutes-Seconds, and Month-Date. Only a single so-called Time-button switch is required in the Time-mode to select any one of these functions. A momentary depression of the Time-button brings about a four-digit display of Hours-Minutes with a colon therebetween. After a predetermined brief dwell period (1.5 to 2.0 seconds), the Hours-Minutes display turns off automatically, the watch reverting to its Normal-mode in which the display is quiescent but the computer continues to operate.
If the Time-button is pressed in and then held, the Hours-Minutes will be presented for the brief dwell period, after which it is replaced by a display of Minutes-Seconds. This Minutes-Seconds display will continue until the Time-button is released.
But if the Time-button is first pressed in momentarily to produce the Hours-Minutes display and the button is again pressed in before the dwell period associated with this display runs out, the Hours-Minutes display will be replaced by a Month-Date presentation which remains on until the Time-button is released. However, if the second depression of the Time-button is momentary, the Month-Date presentation will stay on for a predetermined dwell period (1.5 seconds) and then turn off automatically.
Hence with respect to the various time display functions, once the Time-button of the LSI movement is released, the display will either shut off immediately or turn off automatically when the dwell period associated with the particular time function then in effect runs out. There is no danger, therefore, when operating in the Time-mode that the display will remain on and proceed to drain the battery by reason of the user's failure to operate the Time-button correctly.
However, this danger does exist in the Set-mode of an LSI movement or with a solid-state watch having a similar setting system. The LSI movement, in addition to the Time-button, includes a Set-button which permits simple and precise time synchronization and simple hour changes for time zone and daylight savings time.
In the Set-mode, pressing and releasing the Set-button once will cause the Hours alone to appear on the display. If now the Time-button is pressed, each depression thereof will cause the Hours to advance one count. Hence to set the Hours, one repeatedly presses the Time-button until the correct hour appears on the display. When, thereafter, the Set-button is again pressed and released, the Minutes and Seconds will then appear on the display. In this setting state, each depression of the Time-button will cause the Minutes to advance one count and the Seconds to reset to zero.
Pressing and releasing the Set-button of the LSI movement three times puts the setting system into the Months state and bring about a display of the number of the month. Thereafter, each depression of the Time-button causes the number of the month to advance one count. Pressing and releasing the Set-button four times will cause the Date to be displayed. Thereafter, each depression of the Time-button will advance the date one count.
Pressing and releasing the Set-button five times will cause the digits at each station of the LED display to present all of its segments. Since each LED is made up of seven segments, the number 8 is presented at each station. The purpose of the display is to show whether all LED segments at all four stations are in working condition. Hence this state in the Set-mode is the test state.
Pressing and releasing the Set-button six times causes it to revert to its Normal-mode. Thus in the Set-mode, the number of times the Set-button is successively pressed-in and released determines the setting state in effect, and by actuating the Set-button six times one goes through a cycle of five setting states, followed by a return to the Normal-mode.
Once the display is back in the Normal-mode, then regardless of how carelessly the Time-button is operated by the user, the display will, as explained previously, always turn off automatically either the moment the Time-button is released or shortly thereafter. But in the Set-mode, the failure to return the display to the Normal-mode after carrying out a setting operation may be fatal to the life of the battery powering the LED display.
For example, if after actuating the Set-button four times to put the display in the Date-setting state, the user is distracted and forgets to return the display to the Normal-mode but continues to wear the watch, the display will then remain on continuously in this setting state. As a consequence, current from the battery for the LED display will be drawn uninterruptedly, and the battery will be exhausted in a matter of hours.
A more typical situation involving the Set-button is the jeweler who stocks such solid-state watches and has occasion to demonstrate the question thereof to potential customers. There is a fair chance that the busy or thoughtless jeweler, after explaining to his prospect how the setting system operates will thereafter return the watch to stock in the Set-mode. As a result, the next time the jeweler has occasion to make a demonstration he will find that the watch is inoperative.